Target AFR log graph
Target AFR log graph
This is an EvoScan log of 0x32... which I've read is the target AFR as seen in the fuel tables. I used the following formula to derive the AFR numbers from the byte value: (128/x)*14.7.
The blue line is a 2nd to 3rd pull. The red line is a 3rd gear pull.
I won't post my fuel tables because I haven't altered them from my custom tune by Al. Using this graph it seems like the car is running in the 180-190 load range.
Mods: 3" exhaust with HFC, MBC set to 20psi using manifold pressure, 272/264 GSC cams with stock cam gears, Walbro
The blue line is a 2nd to 3rd pull. The red line is a 3rd gear pull.
I won't post my fuel tables because I haven't altered them from my custom tune by Al. Using this graph it seems like the car is running in the 180-190 load range.
Mods: 3" exhaust with HFC, MBC set to 20psi using manifold pressure, 272/264 GSC cams with stock cam gears, Walbro
Interesting.
However, if you're pushing 20 psi, then you should be hitting load cells in the 200's, especially after initial spoolup, which is when the stock turbo hits hardest.
l8r)
However, if you're pushing 20 psi, then you should be hitting load cells in the 200's, especially after initial spoolup, which is when the stock turbo hits hardest.
l8r)
Code:
RPM MAS(Hz) 2531.25 289.34 2531.25 301.92 2531.25 301.92 2562.5 308.21 2625 320.79 2687.5 333.37 2687.5 345.95 2718.75 352.24 2750 364.82 2812.5 377.4 2843.75 389.98 2843.75 402.56 2906.25 421.43 2968.75 434.01 3000 446.59 3031.25 465.46 3093.75 490.62 3125 509.49 3187.5 528.36 3218.75 559.81 3281.25 584.97 3343.75 616.42 3375 654.16 3437.5 679.32 3468.75 729.64 3562.5 761.09 3593.75 811.41 3656.25 861.73 3750 930.92 3812.5 974.95 3875 1044.14 3906.25 1094.46 4031.25 1151.07 4093.75 1182.52 4156.25 1188.81 4218.75 1169.94 4343.75 1188.81 4406.25 1195.1 4468.75 1220.26 4562.5 1251.71 4687.5 1295.74 4718.75 1327.19 4906.25 1346.06 4968.75 1346.06 5062.5 1339.77 5125 1352.35 5218.75 1364.93 5250 1396.38 5343.75 1434.12 5437.5 1465.57 5500 1484.44 5562.5 1490.73 5625 1509.6 5718.75 1522.18 5781.25 1541.05 5843.75 1553.63 5906.25 1572.5 5968.75 1585.08 6062.5 1597.66 6125 1603.95 6187.5 1603.95
If you use Eric's formula (MAF_Hz/RPM*852) to estimate your load, you'll see that you seem to be landing in the 220-250 load range, which sounds right. You should be able to validate that with a log of your timing numbers.
l8r)
l8r)
Newbie
Joined: Jan 2006
Posts: 29
Likes: 0
From: New Mexico
is that a full throttle run ???
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
Originally Posted by Kyle_Y
is that a full throttle run ???
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
d
Originally Posted by Kyle_Y
is that a full throttle run ???
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
if it is .. by the look of your MAF freqs, you have a laggy car
at 19psi, I hit 12-1300hz by 3500rpms .. and peaks out the reading by 4800rpms..
have a reference at some of the logs posted here .. that seems to be the norm ..
Case in point, when running 25psi, I hit 1048hz at 3500rpm, 1654 at 5500 rpm.
When running 21psi, i hit 958 at 3500rpm, 1649 at 6500rpm
Simple things like upgraded IC pipes and intercoolers and such can change the MAF HZ #s.
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Originally Posted by Evo_Kid
How did you log AFR with evoscan, would love to know.
You can't, but it will log if you have a wideband hooked up to your PC (althought this hasn't been implemented correctly yet).
Newbie
Joined: Jan 2006
Posts: 29
Likes: 0
From: New Mexico
Originally Posted by razorlab
MAF HZ isn't boost, so you can't tell if the car is laggy or not by reading them. Also MAF HZ changes with different cars and mods.
Case in point, when running 25psi, I hit 1048hz at 3500rpm, 1654 at 5500 rpm.
When running 21psi, i hit 958 at 3500rpm, 1649 at 6500rpm
Simple things like upgraded IC pipes and intercoolers and such can change the MAF HZ #s.
Case in point, when running 25psi, I hit 1048hz at 3500rpm, 1654 at 5500 rpm.
When running 21psi, i hit 958 at 3500rpm, 1649 at 6500rpm
Simple things like upgraded IC pipes and intercoolers and such can change the MAF HZ #s.
Hz is a measurement of amount of air being ingested .. higher freqs just mean more air relatively .. the changes you mentioned is a modifier that just shifts the freq curve up or down (if you can convert Hz to lb/min .. you'll see the relationship)
Your case study just proves my point
At 25 psi at 3500rpms because that's where your boost peaks .. but at 6500rpms .. there's where it most likely tapers to almost the same as your 21psi
of course unless you're not using stock turbo
in that case, your VE at higher rpms are not very good and you're actually not making much power at 25psi vs 21 psi ..Anyway .. there's one point which I overlooked
.. altitude !
Originally Posted by donour
What!? In New Mexico I see _half_ of that. 6-700 hz at 3500 rpm.
at 5000' I'm seeing close to only 60-70% of what I mentioned !
if i used hyper terminal to do my afr graph im not sure how i would know when i started my pull unless i just watch when i see the afr drop fast. but i usually watch my afr gauge during my pulls
the stock ECU interpolates boost my MAF frequency, so I'm sure its possible.. the problem is what its doing is determining the VE of the engine, and extrapolating boost value (and of course correcting the value) from it..
Big turbos, or changes in engine displacement, or altering the MAF reading (either via intercept device like an S-AFC or aftermarket modifications to the intake tract) can wreak havoc on that and can no longer represent a constent value.
Big turbos, or changes in engine displacement, or altering the MAF reading (either via intercept device like an S-AFC or aftermarket modifications to the intake tract) can wreak havoc on that and can no longer represent a constent value.
Originally Posted by Evo_Kid
How did you log AFR with evoscan, would love to know.
What causes the flat spots in the spool-up RPM range? Should the mixture be that lean during spool-up? My wideband show it as being in the high 12, low 13 range during spool-up. I'll post overlaid graphs showing target AFR and actual AFR once my USB-to-serial converter shows up.
